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Existing virtio-blk protocol doesn't have DISCARD/WRITE ZEROES commands support, this will impact the performance when using SSD backend over file systems. Commit 88c85538 "virtio-blk: add discard and write zeroes features to specification"(see https://github.com/oasis-tcs/virtio-spec) extended existing virtio-blk protocol, adding extra DISCARD and WRITE ZEROES commands support.

Existing virtio-blk protocol doesn't have DISCARD/WRITE ZEROES commands support, this will impact the performance when using SSD backend over file systems. Commit 88c85538 "virtio-blk: add discard and write zeroes features to specification"(see https://github.com/oasis-tcs/virtio-spec) extended existing virtio-blk protocol, adding extra DISCARD and WRITE ZEROES commands support.